(1) Field of the Invention
The present invention relates to a method for producing a metal matrix composite material, and more particularly, to a method for producing a thin sheet of a SiC-reinforced metal matrix composite material using plasma spraying.
(2) Background of the Related Art
The metal matrix composite material is highlighted as a thermal management material for various electronic devices, such as a heat sink for electronic packages, in that its heat transfer coefficient and thermal expansion coefficient are easily controlled according to the kind and fraction of its reinforcing material. Also, there are actively conducted studies on a method for producing composite materials using various matrix metals and reinforcing materials. Particularly, for use as the thermal management material for electronic devices, materials with the properties of low thermal expansion coefficient, high thermal conductivity, low density and low production cost are centrally developed. In case of an aluminum matrix composite material, a high fraction of the reinforcing material is essentially required to satisfy the low thermal expansion coefficient of the composite material. For example, in a SiC-reinforced aluminum matrix composite material, there is required a SiC volume fraction of about 40–70%. If the volume fraction of SiC in the SiC-reinforced composite material is less than 40%, the thermal expansion coefficient of the composite material will be excessively increased to more than 15.5×10−6/° C., whereas if the SiC volume fraction is more than 70%, the thermal conductivity of the composite material will be too much reduced to 149 W/m·K. Thus, the composite material containing the reinforcing material at an amount out of the range of about 40–70% will be unsuitable for use as the thermal management material for electronic packages.
In producing an aluminum matrix composite material containing a reinforcing material at a volume fraction of more than 40%, there were mainly used a pressure infiltration method or a pressureless infiltration method developed by Lanxide Technology Company, etc., which are disclosed in U.S. Pat. No. 6,228,453 and U.S. Pat. No. 5,856,025. However, such infiltration methods have significant difficulty in producing a preform, and post-production processing is substantially impossible so that subsequent processes are extremely limited. As a result, such infiltration methods has disadvantages in that production cost is increased due to a complicated production process, and also productivity is reduced. Particularly, there is significant difficulty in cutting and processing into a thin sheet shape constituting a measure of the utility of the composite material, and thus, such infiltration methods require expensive cutting and processing, including electrical discharge machining (EDM), laser cutting, processing with diamond tools, and the like.